Biology subjects

Neumann, I.

Publications and source records attributed to Neumann, I..

5 recordsLinked to original sources

bioRxiv2026

Sex-dependent involvement of lateral septum astrocytes in social fear: Role of oxytocin receptor signaling

Astrocytes are now widely recognized as important modulators of synaptic plasticity and socio-emotional behaviors. Recent studies highlight their involvement in anxiety- and depressive-like behaviors, particularly via oxytocin (OXT) signaling. While the specific contributions of astrocytes remain largely unexplored, the role of OXT receptor (OXTR) signaling in the lateral septum (LS) in regulating social fear expression has been well characterized. Here, we studied the differential contribution of astrocytic OXTR signaling using a social fear conditioning (SFC+) paradigm. We found the highest abundance of astrocytes, and especially of OXTR-expressing (OXTR+) astrocytes, within the caudal LC (LSc) compared to the rostral LS in both male and female mice. Interestingly, female mice displayed a significantly higher number of astrocytes and OXTR+ astrocytes in the LSc in comparison to males. However, social fear acquisition resulted in dynamic changes in LSc astrocytic morphology and calcium activity in male mice. Furthermore, we showed that pre-SFC acquisition pharmacology-induced loss of local astrocytic function facilitated the extinction of social fear in males. In support, astrocyte-specific OXTR knockdown in the LSc also facilitated social fear extinction in both males and females. Taken together, our study identifies OXTR-signaling in LSc astrocytes as a crucial component in the mechanisms underlying the regulation of social fear in a sex-dependent manner.

neuroscience↗

bioRxiv2026

Astrocytes control oxytocin-based maternal behavior via connexin 30

Prosocial and affiliative behaviors rely on complex neuroendocrine neuronal circuits. Dynamic neuroglial interactions play prominent roles in shaping synaptic networks, whose alterations contribute to psychiatric disorders associated with social deficits. However, a role for astrocytes in regulating maternal behavior remains elusive. Here we show that female mice exhibiting increased oxytocin levels in the hypothalamic supraoptic nucleus upon social interactions with pups display neuroglial structural plasticity and downregulation of astroglial connexin 30, a protein involved in morphological remodeling. We found that impairing astroglial connexin 30 expression alters the structural properties of astrocytes by decreasing their volume and coverage of oxytocinergic synapses in the supraoptic nucleus of female mice. This functionally sets levels of plasma oxytocin and maternal behavior, exacerbating maternal care in virgin pup-naive female mice deficient for astroglial Cx30. Hypothalamic astrocytes, via connexin 30, are thus key determinants of oxytocin-based maternal behavior, whose alteration is known to impair social skills development in offspring.

neuroscience↗

bioRxiv2024

Oxytocin Gαi signaling-induced amygdala astrocytes processes retraction shapes behavioral stress response

Anticipated reactions to stressful situations are vital for the survival and well-being of organisms, and abnormal reactions are involved in stress-related disorders. The neuropeptide oxytocin is a key modulator ensuring well-adapted stress responses. Oxytocin acts on both neurons and astrocytes, but the molecular and cellular mechanisms mediating stress response remain poorly understood. Here, we focus on the amygdala, a crucial hub that integrates and processes sensory information through oxytocin- dependent mechanisms. Using an acute stress paradigm in mice, genetic and pharmacological manipulations combined with proteomic, morphological, electrophysiological and behavioral approaches, we reveal that oxytocinergic modulation of the freezing response to stress is mediated by transient Gi-dependent retraction of astrocytic processes, followed by enhanced neuronal sensitivity to extracellular potassium in the amygdala. Our findings elucidate a pivotal role for astrocytes morphology- dependent modulation of brain circuits that is required for proper anticipated behavioral response to stressful situations.

neuroscience↗

bioRxiv2021

Modelling sexual violence in male rats: The sexual aggression test (SxAT)

Sexual assault and rape are crimes that impact victims worldwide. Although the psychosocial and eco-evolutionary factors associated with this antisocial behavior have repeatedly been studied, the underlying neurobiological mechanisms are still unknown mainly due to the lack of an appropriate animal model of sexual aggression (SxA). Here, we established a novel paradigm to provoke and subsequently assess SxA in adult male Wistar rats: the sexual aggression test (SxAT). Briefly, male Wistar rats are sexually aroused by a receptive female, which is exchanged by a non-receptive female immediately after the first intromission. This protocol elicits forced mounting (FM) and aggressive behavior (AB) towards the non-receptive female to different degrees, which can be scored. In a series of experiments we can show that SxA behavior is a relatively stable trait in rats and correlates positively with sexual motivation. Rats with innate abnormal anxiety and aggressive behavior also show abnormal SxA behavior. In addition, central infusion of oxytocin moderately inhibits AB, but increases FM. Finally, we identified the agranular insular cortex to be specifically activated by SxA, and inhibition of this region mildly decreased AB during the SxAT. Altogether, the SxAT is a paradigm that can be readily implemented in behavioral laboratories as a valuable tool to find answers regarding the biological mechanisms underlying SxA in humans, as well as social decision-making in general.

neuroscience↗

bioRxiv2021

Loss of the cleaved-protamine 2 domain leads to incomplete histone-to-protamine exchange and infertility in mice

Protamines are unique sperm-specific proteins that package and protect paternal chromatin until fertilization. A subset of mammalian species expresses two protamines (PRM1 and PRM2), while in others PRM1 is sufficient for sperm chromatin packaging. Alterations of the species-specific ratio between PRM1 and PRM2 are associated with infertility. Unlike PRM1, PRM2 is generated as a precursor protein consisting of a highly conserved N-terminal domain, termed cleaved PRM2 (cP2), which is consecutively trimmed off during chromatin condensation. The carboxyterminal part, called mature PRM2 (mP2), interacts with DNA and together with PRM1, mediates chromatin-hypercondensation. The removal of the cP2 domain is believed to be imperative for proper chromatin condensation, yet, the role of cP2 is not yet understood. We generated mice lacking the cP2 domain while the mP2 is still expressed. We show that the cP2 domain is indispensable for complete sperm chromatin protamination and male mouse fertility. cP2 deficient sperm show incomplete PRM2 incorporation, resulting in a severely altered protamine ratio, retention of transition proteins and aberrant retention of the testis specific histone variant H2A.L.2. During epididymal transit, cP2 deficient sperm seem to undergo ROS mediated degradation leading to complete DNA fragmentation. The cP2 domain therefore seems to be a key aspect in the complex crosstalk between histones, transition proteins and protamines during sperm chromatin condensation. Overall, we present the first step towards understanding the role of the cP2 domain in paternal chromatin packaging and open up avenues for further research.

genetics↗